1. Field of the Invention
The present invention relates to a door safety system, which controls an opening and closing of doors if a person or an obstacle is getting near an automatic door provided at an entrance or an exit of building, or a moving door which is used for an opening and closing door of an elevator, or an door of vehicle, and which prevents the person or the obstacle from colliding with the door until when the person or the obstacle pass through the door.
2. Description of the Related Art
An activation switch such as a proximity switch, which opens a door by detecting that a person is getting near an entrance or an exit, or a touch switch, which opens a door by a person touching a part of the door, is used for an automatic door system provided at the entrance or the exit of building.
Conventionally, in addition to the above activation switch, there was provided with a safety light switch, provided at an entrance or an exit of building, for detecting whether or not there is a person so as to prevent the person from being caught by doors when the person stops at the entrance or the exit.
For example, as shown in FIG. 1A, a light emitting device 103 and a light receiving device 104 are respectively provided at a pole 101 and a pole 102, which are respectively located at a left side and a right side of an entrance, so that the device 103 and the device 104 face each other. This light switch is referred to as "a translucent-type light switch" hereinafter. Therefore, it is judged that there is a person 105, if a light passing between the devices 103 and 104 is interrupted. Alternatively, as shown in FIG. 1B, a reflex-type light switch, wherein a light emitting device 106 and a light receiving device 107 are provided at the pole 101 in parallel, can be used for detecting the person 105 by receiving a reflected light. The translucent-type light switch shown in FIG. 1A has a detectable area having a long distance, but the area is narrow like a spotlight. Therefore, for the safety side, it is necessary to provide a plurality of switches. On the other hand, the reflex-type light switch has a relatively wide detectable area, but there is a drawback that the switch does not have a long detectable distance.
Furthermore, a door safety system, wherein the translucent-type light switch and the reflex-type light switch are used together, is described in the unexamined patent publication No. Hei 6 (1994)-66065, the application of which is filed by the present applicant.
However, there is a problem that the above light switch has an insensible area, since light has a character that it goes straight on ahead, and therefore, the sensible area is limited accordingly. Furthermore, an activation switch and two kinds of safety switches should be provided in order to control an opening and a closing of doors, and therefore, there is a problem that an additional constructional work is also necessary. There is a desire that the additional construction work with respect to poles, floors or the like is decreased as less as possible. If a safety and activation sensor for preventing a collision is used, there is a possibility that an opposite door, or pole, or wall of building is detected by the sensor. Therefore, a safety and activation wide range detection sensor, which only detect a person passing through doors without detecting a device or a structural object around the doors, is desired. Furthermore, it was desired that an apparatus provided at the door has low energy consumption, and in order to improve a reliability of an apparatus, it was very important to supply electric power to the apparatus provided at the door from building without contact.
With reference to FIG. 2A, the fact that there is a high possibility that the above light-type activation switch has an insensible area will be explained hereinafter. As shown in FIG. 2A, reflex-type non-contact proximity switches 110a, 110b are provided at a building side, which is close to a central part of automatic doors 4, 5 provided at an entrance and an exit. FIG. 2B is a top view of this construction. Sensible areas 120a, 120b are provided so that the sensible areas are not influenced by movements of the doors. Therefore, an area 122a including a moving space of the doors constitutes an insensible area, and it was impossible to detect a person or an obstacle within the area 122a. FIG. 2c is a cross-sectional view of the insensible area. A distance between an inner side lla of the non-contact proximity switch 110a and the door 4 or 5, and a distance between an inner side 111b of the non-contact proximity switch 110b and the door 4 or 5 should be greater than 50 mm. The width of the insensible area 122b was about 150-300 mm. Therefore, auxiliary light switches were provided at an immovable portion of building so as to prevent a person, for example a child, from being caught by closing doors, even if the person stops within the sensible area. However, it was impossible to detect the person within the moving area of the doors 4, 5.
Furthermore, in the case of the reflex-type non-contact proximity switch, if a distance between the proximity switch and a person or an obstacle is relatively changed, an output of a sensor is greatly varied. It is easy to provide a circuit construction wherein a switching operation for detecting moving objects is performed by using a detecting signal, which corresponds to a difference of sensor outputs. However, there is a problem that it is impossible to detect a person just standing in front of the sensor by only using the switching operation. On the other hand, if a switching operation for detecting an immovable person or obstacle was performed, it was very difficult to perform it, since output of a sensor, a temperature drift of the sensor, and a sensible range of the sensor are greatly varied.
Furthermore, since doors are always moving, a disconnection of a cable may happen. It becomes a cause of failure or trouble to provide sensors and an apparatus at a side of moving doors, and therefore, it should be avoided. If the sensors and the apparatus are provided at the doors, it is desired that energy consumption is decreased as less as possible, and then, a method wherein electric power is supplied from an immovable portion of building to moving doors without electrical contact, is generally used.
In a case of moving doors used for an elevator system, since moving distances of the doors are short, it is necessary to detect a person or an obstacle within a vary narrow space. Additionally, in this case, since a speed for opening and closing doors is relatively low compared with doors for building, a sensor for detecting a person or an obstacle without any electrical contact is not practically used. Therefore, by associating a contact sensor with the moving doors, it is detected that a person is caught between the doors, and then, the doors start opening. Furthermore, in case of an automatic door system or an automatic window system used for a vehicle such as a train, an automobile or the like, a space for mounting a safety sensor tends to be limited to a very narrow space. Therefore, for the time being, a non-contact-type door safety system is not practically used.